Work disability among persons with musculoskeletal conditions is rising both absolutely and relative to the rate among persons with other chronic conditions. In contrast to prior efforts, the proposed study uses a national, community-based longitudinal data base to study the causes and consequences of work disability among persons with musculoskeletal conditions. Specifically, the project will: 1) estimate the incidence and prevalence work disability among persons with musculoskeletal conditions; 2) compare the incidence and prevalence work disability of such persons and those with other forms of chronic disease; 3) test models of the causes of work disability among persons with musculoskeletal conditions; and 4), describe the impact of musculoskeletal conditions on the labor force participation of family members and on the economic well-being of the family. The project will test a dynamic model in which the transformation of the economy accounts for much of the rise in the work disability rate among persons with musculoskeletal conditions. This process is hypothesized to disproportionately displace persons with musculoskeletal conditions from manufacturing jobs with a declining share of employment, while failing to yield them a proportionate number of jobs in the service sector with a rising share of employment. In this model, the effect of industrial transformation is independent of the medical or social characteristics of these persons, the physical and social characteristics of their jobs, and their potential to replace lost earning with disability benefits. The model will be tested with data from the National Health and Recruitment Study (HRS). The HRS derives from a national, probability sample of 13,500 persons ages 51-61 years, who will be followed from 1992 through 2004 through bi-annual interviews, and data collected from employers, vital records, and the Social Security systems. The HRS is specifically designed to develop causal models of work disability. The results of this project should help in the design of public policies to reduce the prevalence of work disability among persons with musculoskeletal conditions, specifically by monitoring the equal employment provisions of the Americans with Disabilities Act of 1990, and by targeting vocational rehabilitation efforts on growth sectors of the economy.